"Aikido doesn't require fitness so most aikido players are old, fat and not strong enough"

It's the same as any other martial art. If you're fat and out of shape, you'll be slow and your ability to apply "techniques" will be hindered.

I picked up a book by the Ueshibas the other day. They said in that book that your Aikido is contingent on speed. Seeings that we all accept that a 200 lbs fat person will move slower than a 100 lbs slender person, seems to me that that's evidence that to be good at Aikido (in the physically effective way) thinner is better.

Like someone else said: don't confuse the art with the artist. Aikido's not a fat persons art (IMO), it's just an art that some fat people practice.

Ask your buddys if there's any old people in their art. If so, why are they talking about Aikidoka's ages. If not, shouldn't they be concerned that they're practicing an art that they will not be able to practice for good?...unlike you who can practice Aikido for the rest of your life.

As far as strength goes: as an Aikidoka, I'd rather work smart, not hard. Ask those numbskulls if they want to push a car on flat tires if it's not necessary...point: strength isn't necessary when you make the smart decision...Aikido.